Transcript Characteristics of Stars - Laconia School District

Characteristics of Stars
By: Kendra, Paige, and Brandon
Constellations
• Constellations are an imaginary pattern of
stars in the sky. The ancient observers found
this out first. They imagined this though. The
ancient observers saw that the stars made
animals and people in the sky.
Apparent Brightness
• Apparent brightness is seen from
Earth. The astronomers can measure
apparent brightness fairly easy using
electronic devices.
Absolute Brightness
• Absolute brightness is the brightness
of the star that would have if it were at
a standard distance from Earth.
Spectrograph
• A spectrograph is a device that breaks
into colors and produces an image of
resulting spectrum. Most large
telescopes have spectrums.
Light-Year
• The distance that light travels in one
year, about 9.5 million million
kilometers.
Parallax
• A parallax is the apparent change in
position of an object when you look at
it from different places. For an example,
image that you and a friend have gone
to a movie. A man with a large hat sits
down in front of you. Because you and
your friend are sitting in in different
places he covers half of the screen.
Hertzsprung-Russell Diagram
• People say about 100 years ago, two
scientists were working alone and
made this discovery. Both Ejnar
Hertzsprung in Denmark and Henry
Norris Russell in the United States,
they made these graphs to find out if
the temperature and the absolute
brightness of the stars related. This
was called the Hertzsprung- Russell
Diagram.
Main Sequence
• A main sequence is the diagonal on an
H-R diagram that includes more than 90
percent of all stars.
Key Concept #1.
• How are stars classified?
• Stars are classified by their color,
temperatures, sizes, and brightness
Key Concept #2.
• How do astronomers measure distance to the stars?
• Astronomers use a method called parallax. Because
of the Earth's revolution about the sun, near stars
seem to shift their position against the farther stars.
The smaller the parallax shift, the farther away from
earth the star is. This method is only accurate for
stars within a few hundred light-years of Earth. When
the stars are very far away, the parallax shift is too
small to measure.
Key Concept #3.
• What is an H-R diagram and how do
astronomers use it.
• The H-R diagram can be thought of as a
graph, with color (temperature) on the x-axis
and luminosity on the y-axis. Since stars go
through a definite "life cycle" which can be
mapped on the H-R diagram, a star's location
on the diagram can indicate both its mass
and its relative age.
Figure #1.
• How many times larger is this than the
sun, which has a diameter of 1.4 million
kilometers?
Figure #2.
• Why do the closer street lights appear bigger
than the more distant lights?
• Because the brightness depends on the both
its size and temperature. The closer you are
to a light it seems better.
Figure #3.
• Why do nearby stars
appear to change
position between
January and July?
Look at the image to
the right and figure it
out.
Reading checkpoint #1.
• What is a spectrograph?
• A device that breaks light into colors
and produces an image of the resulting
spectrum.
Reading Checkpoint #2.
• What is a star’s absolute brightness?
• The brightness a star would have if it
was standing a distance from Earth.
Reading Checkpoint #3.
• How is a parallax useful in astronomy?
Reading Checkpoint #4.
• What is the main sequence?
• The main sequence is the diagonal region
in the H-R diagram.
Assessment #1.
• Name three characteristics used to
classify stars.
• Size
• Temperature
• Brightness
Assessment #2.
• What is the difference between apparent
brightness and absolute brightness?
The difference between apparent brightness
and absolute brightness is
Assessment #4.
• What is a light-year?
• The distance that light travels in one
year, about 9.5 million million
kilometers.
Assessment #5.
• What is a parallax?
• A parallax is the apparent change in
position of an object when you look at
it from different places
Assessment #6.
• Identify two ways in which astronomers
can use the H-R diagram.
• Astronomers can use the H-R diagram
for classifying stars and to understand
how stars change over time.
THE ENDD :D
Alright, we worked on this for 4 days. It
took us a lot of time and a lot of effort,
we also put a lot of effort into this twoo.
So…really, we hope you liked it. Now
you may clap :D.
By: Brandon, Kendra, and Paige :D.